Μm Particle Size Research Articles

10 μm-Level TiNb2 O7 Secondary Particles for Fast-Charging Lithium-Ion Batteries.

TiNb2 O7 with Wadsley-Roth phase delivers double theoretical specific capacity and similar working potential in comparison to spinel Li4 Ti5 O12 , the commercial high-rate anode material, and thus can enable much higher energy density of lithium-ion batteries. However, the inter-particle resistance within the high-mass-loading TiNb2 O7 electrode would impede the capacity release for practical application, especially under fast-charging conditions. Herein, 10-20 μm-size carbon-coated TiNb2 O7 secondary particle (SP-TiNb2 O7 ) consisting of initial micro-scale TiNb2 O7 particles (MP-TiNb2 O7 ) was fabricated. The high crystallinity of active material could enable fast-charge diffusion and electrochemical reaction rate within particles, and the small number of stacking layers of SP-TiNb2 O7 could reduce the large inter-particle resistance that regular particle electrode often possess and achieve high compaction density of electrodes with high mass loading. The investigation on materials structure and electrochemical reaction kinetics verified the advances of the as-fabricated SP-TiNb2 O7 in achieving superior electrochemical performance. The SP-TiNb2 O7 exhibited high reversible capacity of 292.7 mAh g-1 in the potential range of 1-3 V (Li+ /Li) at 0.1 C, delivering high-capacity release of 94.3 %, and high capacity retention of 86 % at 0.5 C for 250 cycles in half cell configuration. Particularly, the advances of such an anode were verified in practical 5 Ah-level laminated full pouch cell. The as-assembled LiFePO4 ||TiNb2 O7 full cell exhibited a high capacity of 5.08 Ah at high charging rate of 6 C (77.9 % of that at 0.2 C of 6.52 Ah), as well as an ultralow capacity decay rate of 0.0352 % for 250 cycles at 1 C, suggesting the great potential for practical fast-charging lithium-ion batteries.

Toxicokinetics of rare earth element oxides administered intravenously to rats

Rare earth elements (REEs) are increasingly used in a wide range of applications. However, their toxicokinetic behaviors in animals and humans are not yet fully documented, hindering health risk assessments. We used a rat experimental model to provide novel data on the toxicokinetics of the insoluble oxide forms of praseodymium (Pr), neodymium (Nd), cerium (Ce) and yttrium (Y) administered intravenously. Detailed blood, urinary and fecal time courses were documented through serial sampling over 21 days in male Sprague-Dawley rats exposed to a mixture of these REE oxides administered at two different doses (0.3 or 1 mg kg−1 bw of each REE oxide commercially sold as bulk μm-sized particles). Tissue REE levels at the time of sacrifice were also measured. Significant effects of the dose on REE time courses in blood and on cumulative urinary and fecal excretion rates were observed for all four REE oxides assessed, as lower cumulative excretion rates were noted at the higher REE dose. In the liver, the main accumulation organ, the fraction of the administered REE dose remaining in the tissue at necropsy was similar at both doses. Toxicokinetic data for the REE oxides were compared to similar data for their chloride salts (also administered intravenously in a mixture, at 0.3 and 1 mg kg−1 bw of each REE chloride) obtained from a previous study. Compared to their chloride counterparts, faster elimination of REE oxides from the blood was observed in the first hours post-dosing. Furthermore, higher mean residence time (MRT) values as well as slower cumulative urinary and fecal excretion were determined for the REE oxides. Also, while liver REE retention was similar for both REE forms, the fractions of the administered REEs recovered in the spleen and lungs were noticeably higher for the REE oxides, at both dose levels. This study highlights the importance of both the dose and form of the administered REEs on their toxicokinetic profiles. Results indicate that chronic exposure and increased doses of REEs may favor bioaccumulation in the body, in particular for insoluble oxide forms of REEs, which are eliminated more slowly from the body.

Determination of Clorsulon and its related substances in commercial bulk drug substance batches by a rapid ion-pair UPLC method

Clorsulon is a potent anthelmintic agent and is widely used for the treatment and control of parasites including adult liver flukes in cattle and sheep. A rapid ion-paired reversed phase ultraperformance liquid chromatography (IP-UPLC) method has been developed and validated for determination of Clorsulon and its related substances in bulk drug substance batches of Clorsulon with a short octadecyl column. Analytes were eluted by a gradient elution on a Acquity UPLC® BEH C18 column (50 mm × 2.1 mm i.d., 1.7 µm particle size). Column temperature was maintained at 55 °C and all analytes were monitored by UV detection at 268 nm. Mobile phase-A constitutes 3 mM tetrabutylammonium hydroxide in H2O and mobile phase-B constitutes acetonitrile/methanol (50/50, v/v), respectively. All analytes of interest were adequately separated within 5 min. The analytes were quantitated against an external reference standard of Clorsulon. The chemical structures of degradation products of Clorsulon were proposed based on two-dimensional UPLC-MS data. The IP-UPLC method has been successfully validated and demonstrated to be accurate, sensitive, robust, and specific.

Bio-analytical Method for the Pre-clinical Estimation of Donepezil Hydrochloride in Rabbit Plasma by RP-HPLC

A simple, reliable and sensitive RP-HPLC bioanalytical method with PDA as detector was developed for the estimation of donepezil HCl in the rabbit plasma and validated. The biological samples were extracted and analysed using loratadine as internal standard. The sample analysed with Inertsil ODS 150mm x 4.6mm, 5.0µm particle size column using 70:30 v/v of 0.1% trifluoroacetic acid and acetonitrile mobile phase at flow rate of 1mL/min. All the parameters validated were within the limits proposed in bioanalytical method validation guidelines. The linearity was observed in the range of 5-200ng/mL with LOD of 0.9ng/mL. The method was observed to have short analysis time of 6 min and also found to be successful in studying the pharmacokinetic parameters of donepezil HCl.

Green RP-HPLC methods for assay and related substances in rivaroxaban tablets

AbstractIn this study, two different ethanol-based RP-HPLC methods for assay and quantification of rivaroxaban related substances in tablets were developed, based on green analytical chemistry (GAC) principles, using the design of experiments approach. The chromatographic separation was performed on X-Bridge C18 column (250 × 4.6 mm, 5 µm particle size), using isocratic elution with ethanol : water (35:65, % v/v) for the assay and gradient elution with ethanol/water mobile phase, for related substances, with a flow rate of 1.0 mL min−1. The gradient method was optimized for the separation of three specified impurities (impurity G, impurity H, and impurity 14) and the selectivity was further confirmed using forced degradation studies. Both methods were validated in accordance with ICH guidelines. The robustness of the methods was confirmed with the Central Composite Face Design of Experiments. Analytical Eco-scale approach and AGREE metrics confirmed that both methods are in accordance with the GAC principles. The proposed ethanol-based RP-HPLC methods were applied for assay and determination of related substances in rivaroxaban 10 mg tablets obtained from three different manufacturers available on the Macedonian market.

Experimental study of gas recovery behaviors from methane hydrate-bearing sediments by CO2 replacement below freezing point

Natural gas hydrate (NGH) is one of the most promising clean energy sources in the future because of its huge reserves and cleanliness, and the CO2 replacement method can realize the safe extraction of NGH and the underground storage of greenhouse gases. This study investigates the influence of quartz sand size and ice content on hydrate replacement characteristics below freezing point conditions. Results indicate that, at a temperature of 271.65 K, when particle sizes range from 250 μm to 500 μm, there is an observed increase in CH4 recovery alongside a concurrent decrease in CO2 sequestration as particle size decreases. Additionally, when maintaining a fixed 500 μm particle size, the proportion of quartz sand positively correlates with CH4 recovery. Furthermore, the presence of quartz sand grains in an ice powder system can improve the replacement effect. By contrast, the presence of quartz sand significantly enhances the CO2 sequestration ratio more than the CH4 recovery ratio. In mixed ice-sand porous media, CO2 sequestration can be enhanced from 0.0496 mol to 0.1012 mol, representing a 104 % increase in CO2 sequestration molarity when compared to the pure ice conditions.

Characterizations of some discarded shells particles polymer-based composites for ceilings and particles board applications

Sea-shells, periwinkle-shells, and snail-shells were pulverized into 35.5 µm particle sizes. Using a two-roll Rheomixer with a rotor speed of 60 rpm for 10 minutes, the particles were thoroughly mixed with the binders in ratio 2:1 and placed in the compression mold of dimension 15 cm by 3 cm by 3 cm using a force of 1.5 kN. The Rockwell hardness tester on scale B with a 1.56 mm steel ball, optical microscope and Flexural tester were used to characterize the composites. Thermo-gravimetric analyzer and Fourier Transform Infrared (FTIR) Spectrometer were used to characterize the shell particles. According to the results, epoxy resin (bisphenol-A-diglycidyl ether poly) and hardener (isophoromediamine) composites containing periwinkle shell particles had the highest hardness number of 48 and could withstand maximum flexural load of 5.5 MPa ether poly) and hardener (isophoromediamine) proved to be the best epoxy resin. All the shell particleS functional groups were visible in the FTIR analysis with varying transmittances at their respective wavenumbers. Optical micrographs of the composites showed uniform distribution of the reinforcement and the matrix, thermo-gravimetric analyses demonstrated good thermal stability of the shell-particles up to 250 ◦C

Influence of particle parameters on micro-machining performance of CoCrFeNiAlX/Al composite materials

This study delves into the influence of particle size on the micro-machining performance of CoCrFeNiAlXp/Al composite materials. It employs a combination of experimental and simulation methods to investigate the effect of different particle sizes on the surface integrity of the composite material. The research also scrutinizes the impact of tool particle size on cutting forces, cutting temperatures, and chip morphology across a range of cutting parameters. Additionally, it establishes a clear link between the quality of the machined surface and the relative position of the tool particles. The findings reveal that an increase in particle diameter leads to a reduction in cutting forces. Furthermore, at a constant particle size, an initial rise in cutting speed results in an increased cutting force, which subsequently decreases. Specifically, the maximum cutting force is observed at a particle size of 10 μm, reaching its peak at a cutting speed of 60 m/min, approximately 1.6 times that of the 40 μm particle size. The primary cutting force displays a positive correlation with cutting depth but a negative correlation with particle diameter. For particles of uniform size, an increment in the Al element content initially reduces the cutting force, which subsequently increases, with the minimum force occurring at an Al element molar ratio of 13 %, roughly 60 % of the Al0 particle. Cutting temperature rises with higher cutting speed and depth but inversely correlates with particle diameter and Al content. A particle size of 10 μm generates the highest cutting temperature, approximately 1.4 times that of a 40 μm particle with identical Al content. The completeness of the chip positively correlates with cutting speed, but at a speed of 70 m/min, chip breakage experiences a significant upsurge. The bending radius of the chip increases with cutting depth, ultimately leading to fracture at a depth of 60 μm. A higher Al content in the particles results in more pronounced chip breakage. The optimal surface quality is achieved when the tool is positioned above the particles, while positioning it below or at a 1/2 distance from the particles is more likely to cause damage to the machined surface.

Effect on Fine Particles Output Characteristics of Ceramic Ball Grinding

Steel balls as traditional grinding media are prone to excessive fines generation and high energy consumption. Therefore, in light of this problem, the authors investigated another media—ceramic balls based on the output characteristics of fine particles. This study discusses the effect of ceramic balls on the change of the particle size distribution, zero-order output characteristics, micro-strain, and collision energy in ground products. The results showed that for −10 μm particle size, ceramic balls have a smaller production rate than steel balls. In addition, when the filling rate of ceramic balls is 40%, the yield of −10 μm is reduced compared to steel balls. Therefore, ceramic balls greatly reduced the overgeneration of fines. Additionally, the micro-strain rate of ceramic ball grinding with time is 67% lower than that of steel ball grinding. Furthermore, ceramic balls cannot only mitigate excessive fines generation but also effectively reduce energy consumption.

A Novel, Economical RP-HPLC Method for Quantification of Cefixime in Bulk and Pharmaceutical Solid Dosage form

A new, precise, economical, and linear gradient reverse phase high-performance liquid chromatography (RP-HPLC) method has been developed and validated for assay determination in Cefixime. The chromatographic separation was achieved with Hypersil C18(250*4.6)mmand 3 µm particle size column. The flow rate was 1.0 mL/min and eluents were detected at 220 nm using PDA detector. The retention time was found to be 7.3 min.The percentage recoveries for molecules were found to be in the range of 99–101%. The calibration curve demonstrated good linearity in the range of 20–100 gm/ml. for Cefixime. The approach has been validated in accordance with the International Conference on Harmonization's regulatory criteria. The evaluated parameters are precision, linearity, detection limit, quantification limit, specificity, accuracy, and robustness.The technique may be applied to stability investigations as well as routine analysis to identify and quantify Cefixime in pharmaceutical dosage form .
 Keywords: Cefixim. Reversed Phase High Performance Liquid Chromatography. Assay substances. Methanol

What is environmental DNA?

AbstractDNA collected from the environment (eDNA) can provide valuable understanding of ecological patterns and processes. eDNA is highly physically heterogeneous, but this has not been well‐characterized, so most eDNA sampling strategies do not target any particular physical fraction. Consequently, we have limited evidence to understand and interpret the physical behavior of eDNA, to improve the efficiency of sampling, nor to target components of the eDNA spectrum for taxonomic and molecular attributes. We perform the first detailed characterization of the components of a marine eDNA sample using serial filtering from an 80 to <0.22 μm particle size gradient, a tree of life metabarcoding approach using taxon‐specific and universal assays, coupled with scanning electron microscopy and fluorescent confocal microscopy. We confirm that eDNA is manifest in a broad spectrum of physical states, ranging from extracellular DNA fragments to whole cells, tissue fragments, and whole organisms. The largest of these fractions of eDNA were embedded in microbial biofilms, rather than particulate. We show that the choice of filter size and types can target components of this spectrum, can affect the detectable species richness, and notably, also enrich samples for specific taxonomic groups. Our results imply that there is considerable scope to improve the efficiency of eDNA collection from aquatic environments, and its informativeness.

Characterization of the Aluminum Matrix Composite Reinforced with Silicon Nitride (AA8011/Si3N4) Synthesized by the Stir Casting Route

Abstract: The result of different volume % of Silicon Nitride (Si3N4) in AA 8011 alloy fabricated through stir casting process & then tested for hardness, wear test. Energy Dispersive Spectroscopy (EDS), and Scanning Electron Microscopy (SEM) of these samples are done. It is found that the highest hardness and wear strength can be obtained with the addition of 80 μm particle size of Si3N4 with 6% of its total volume fraction. This increase in the properties is due to the increase in density caused by the addition of Si3N4 reinforcement particles. SEM study also shows that the distribution of Si3N4 with the matrix material. The maximum hardness is obtained at 40.7 HV in sample 04 having 6% of Silicon Nitride (Si3N4) and 94% of Aluminium Alloy 8011, Similarly, maximum wear is recorded in the sample having 6% of Silicon Nitride (Si3N4) and 94% of Aluminium Alloy 8011when the load is 4kg and RPM is 1800.

Mineral Composition Effects on Dust Deposition at Realistic Engine Conditions

Abstract In this article, the role of mineral composition was assessed for Air Force Research Laboratory Test Dust (AFRL), for deposition in a realistic gas turbine engine environment. Experiments were performed on an effusion cooling test article with a coolant flow temperature of 894 K and surface temperature of 1144 K. Aerosolized dust with a 0–10 µm particle size distribution was delivered to the test article. The mineral recipe of AFRL was altered such that the presence of each of the five components ranged from 0% to 100%, and capture efficiency, hole capture efficiency, blockage per gram, and normalized deposit height were reported. Results are compared to a previous study of the intermineral synergies in an impingement cooling jet at the same temperature conditions. Despite differences in experimental facility flow geometry, overall agreement was found between the trends in the deposition behavior of the dust blends. The strong deposition effects that were observed were shown to be related to adhesion forces of particles, mechanical properties, and chemical properties of the dust minerals. Supplemental testing was performed in a high-temperature (1425–1650 K) impinging jet (200–260 m/s) to evaluate mineral effects at hot gas path conditions. Capture efficiency and morphology of dust deposits are reported. The capture efficiency in this regime was shown to correlate well with temperature, with chemical effects being secondary. An attempt was made to predict capture efficiency using chemical assessments such as a ratio of bases to acids, Ca:Si ratio, and optical basicity with only modest success.

A validated green UPLC method for the quantification of synthetic pharmaceutical adulterants in the extract of the aphrodisiac herbal plant ashwagandha (Withania somnifera) and in spiked human plasma

In this work, an ultra-performance liquid chromatographic method was developed and subjected to bioanalytical method validation for screening the root extract of Ashwagandha. The method was also extended for simultaneous determination of Sildenafil, Vardenafil and Avanafil in plant root extract and in human plasma samples to detect the possible counterfeiting of the plant's pharmaceutical products with other synthetic drugs that might endanger the life of their consumers, particularly elderly people, and those with chronic diseases. The method was developed using BDS Hypersil TM C18 column (250 × 4.6 mm and 3 μm particle size) as a stationary phase and a mobile phase consisting of acidified water and acetonitrile in a gradient elution program with a flow rate of 1.00 mL min 1. In the plant extract, the proposed method was found to be linear in the range 1.00–200.0 μg mL−1 for the Vardenafil and Avanafil and 5.00–200.0 μg mL−1 for Sildenafil with a recovery percentage in range of 98.18–101.07 % for the three drugs. Intra-day and inter-day precision ranges were 0.088–1.219 and 0.151–1.313, respectively. The limit of detection and the limit of quantification for Vardenafil and Avanafil were 0.166 μg mL−1 and 0.500 μg mL−1, respectively. Whereas, for Sildenafil 0.333 μg mL−1 and 1.000 μg mL−1. The ICH validation parameters were also demonstrated. Bioanalytical method validation was established following US-FDA recommendations and the method showed good linearity in the range 1.00–200.00 μg mL −1 for Vardenafil and Avanafil, and 5.00–200.00 μg mL −1 for Sildenafil. The results revealed high accuracy with % recovery ranging from 91.05 to 98.91 % for the three drugs. The intra-day and inter-day precision were also conducted, in terms of % relative standard deviation, and ranged from 0.119 to 4.037 % and from 0.223 to 5.062 %, respectively. Furthermore, other validation parameters were evaluated including extraction recovery and stability of the analytes throughout samples preparation and storage for both short- and long-term. The method greenness was evaluated using NEMI, GAPI, AGREE and analytical eco-scale.

The Effect of Different Particle Sizes of SiO2 in Sintering on the Formation of Ternesite

Ternesite is synthesized through sintering a mixture of CaCO3, SiO2, and CaSO4 in a molar ratio of 4:2:1. Ternesite has a hydration rate between ye’elimite and belite in an aluminum-containing environment, and is considered to be a new material that can be used to enhance the performance of calcium sulphoaluminate cements. This experiment investigated the influence of different particle sizes of SiO2 on ternesite formation. Controlled partial pressure sintering was employed within the temperature range from 1100 °C to 1200 °C, with a 72 h incubation period. The highest purity of ternesite in the samples reached 99.47% (500 nm SiO2 sample). The analysis results from scanning electron microscopy and an energy dispersive spectrometer indicated that the particle size of SiO2 exerted a significant influence on the formation of ternesite. In the preparation of ternesite from 10 μm particle size SiO2, traces of calcium silicate were found in the product. The results of a thermal analysis further demonstrated significant distinctions in the thermal stability of ternesite prepared with SiO2 of different particle sizes. Additionally, the crystallinity of ternesite was influenced by the particle size of SiO2, consequently impacting the hydration performance of ternesite–calcium sulphoaluminate cement.

Simultaneous determination of praziquantel, fipronil, eprinomectin, (S)-methoprene, their key related substances and butylated hydroxytoluene (BHT) in a topical veterinary drug product by a single stability indicating high performance liquid chromatography method

A simple, robust and QC (quality control) friendly high performance liquid chromatography (HPLC) method was developed and validated for simultaneous determination of four active pharmaceutical ingredient [namely fipronil, (S)-methoprene, eprinomectin, and praziquantel] and their key degradation products in a broad-spectrum topical finished product. Typical sample of the finished product contains a total of 30-plus peaks of interest. Analytes were separated on a HALO C18 column (150 mm × 4.6 mm i.d., 2.7 µm particle size) with a gradient elution at 50 °C column temperature and 0.6 mL/min flow rate. Detection wavelength of 245 nm is used for praziquantel, eprinomectin and their degradation products, 265 nm for (S)-methoprene and its degradation products and 280 nm for fipronil and its degradation products and for the antioxidant, BHT. Mobile phase of the method is composed of 10 mM potassium phosphate buffer and 1,4- Dioxane (98/2, v/v, pH 5.0) as mobile phase-A, and EtOH/MeOH/MeCN/IPA (86/4/6/4, v/v/v/v) as mobile phase-B. All analytes of interest were adequately separated by this single HPLC method. The stability-indicating capability of the method has been demonstrated by successfully separating the degradation products in the stressed degraded samples of the finished product. Limit of quantitation (LOQ) and limit of detection (LOD) of the method is 0.3% and 0.1% of target analytical concentration for each individual API in the finished product. This method has been demonstrated to be sensitive, robust, specific, accurate and stability-indicating for analysis of the topical drug product containing praziquantel, fipronil, eprinomectin and (S)-methoprene.

Evaluation of the electrical properties of carbon electrodes developed with bio-material additions as a sacrificial anode in cathodic protection

The use of zinc and magnesium sacrificial anodes for the protection of steel structures in cathodic protection techniques have been widely accepted but longevity and environmental friendliness of these materials in service still needs to be improved. Thus, the need to continually develop anodes that can potentially serve the same purpose and/or better performance. This work is a feasibility study on the production of carbon electrodes for possible application as sacrificial anodes for the cathodic protection of mild steel. The main aim of this investigation is to develop an electrode from carbon-based materials with a view to producing anodes that can potentially replace zinc and magnesium electrodes for cathodic protection of low-carbon steel. The electrodes were developed using mixture of coal, charcoal, mill scale, wood dust and coal tar (binder) that were heated and compressed in a metal die. The current passing through the electrodes was measured with the resistance, resistivity and conductivity determined, including the current densities (Iρ) which gives an indication of the electrochemical behavior of the electrodes. Morphology of the electrodes were examined by optical microscope (OM) and scanning electron microscope (SEM) to assess the influence of porosities of the electrodes produced. Based on these findings, it was generally observed that the conductivity increases from 5.23E-4 S/m to 5.87E-3 S/m for 150 µm and 600 µm particle sizes, respectively. Generally, resistivity increases with an increase in the amount of wood dust in the carbon anodes developed. The carbon electrode of 600 µm particle size with the composition of 67 wt% coal, 5 wt% charcoal, 10 wt% coal tar, 10 wt% mill scale and 8 wt% wood dust had the best current density that could offer corrosion protection for mild steel.

Effect of energy input on flotation of particles with different sizes: Perspective of hydrodynamics characteristics

By employing a torque sensor to measure energy input in a flotation machine, this paper investigates the flotation behavior of modified quartz particles with different sizes but similar surface hydrophobicity under various energy input conditions. Numerical simulations of the mechanical flotation machine were conducted to obtain the fluid dynamic characteristics including the flow velocity, turbulence kinetic energy, and turbulent eddy scale. With the flotation results and numerical simulations combined, the potential collision, attachment, and detachment behaviors of fine particles (―45 µm), intermediate particles (45―74 µm), and coarse particles (74―125 µm) were analyzed. The results demonstrate that under different conditions of energy input, the recovery of intermediate-sized particles was optimal for the above size fractions. As the particle size increases, the energy input required to achieve optimal recovery decreases. The flotation rate constants increase nearly linearly with energy input. Compared to the medium-sized particles in the range of 45―74 µm, finer and larger particles exhibit lower floatability. When the energy input exceeds a certain range, no stagnation zone is observed. The rupture of bubble-particle aggregates becomes more pronounced, which may be a reason why flotation recovery begins to decrease. Increasing energy input enhances turbulence energy dissipation and reduces the Kolmogorov turbulence length scale, in this study, the ―45 µm, 45―74 µm, and 74―125 µm particle sizes reached the optimal flotation performance at dp / η values of 1.35, 1.83, 2.54, respectively. The particle diameter-to-integral length scale ratio (dp/L) is also discussed as an important parameter for turbulent dispersion.

Reversed phase HPLC method development and validation for the analysis of amlodipine besylate in tablets dosage form and human plasma

Introduction: Several analytical methods for quantitative determination of amlodipine either in pharmaceuticals or biological fluids have suffered different setbacks. Therefore, we aimed at developing a cost effective, simple, robust, and sensitive reversed phase high performance liquid chromatography (RP-HPLC- UV) method for quantification of amlodipine in dosage form and in human plasma. Method: The separation was performed on an analytical column 150 mm x 4.6 mm i.d., Agilent Eclipse XDB C18 Column packed with 5 μm particle size and protected by a guard column (30 mm x 4.6 mm i.d.). The mobile phase composition contained acetonitrile: phosphate buffer (25 mM KH2PO4) adjusted to pH 3.1 with orthophosphoric acid in the ratio of 45:55 v/v. The flow rate was 1.2 mL/min and the UV detector was set at a wavelength of 240 nm. The column was maintained at ambient temperature. Results: The calibration curve gave good linearity in the concentration range studied. The column efficiency was highly evident by high theoretical plates and small height equivalent to theoretical plate (HETP). The percent relative standard deviation (% RSD) was less than 3% in the inter- and intra-day o assay. Amlodipine, 50 ng/mL in plasma stored frozen at -80 C was stable There was no statistical difference in the precision of amlodipine assayed after 12 months when compared to the initial assay (P>0.05). The % recovery of amlodipine in human plasma was 97.79±0.17% to 99.52±0.63%. Conclusion: The new RP-HPLC method is sensitive, reproducible, precise, accurate and robust. We conclude that the method is suitable for estimation of amlodipine besylate in human plasma for pharmacokinetic studies and assay of pharmaceutical dosage form

Optimization of ultrasonic extraction for enhanced polyphenol profile and antioxidant capacity in mango seeds: A comparative study with thermal extraction

The mango seed (MS) is a by-product with a high content of bioactive compounds and antioxidant capacity (AOX). Ultrasound-assisted extraction (UAE) has been recognized as an efficient technology for the extraction of bioactive compounds in plant materials. Nonetheless, it is essential to optimize the process conditions and compared with conventional technologies. The objective of this study was to compare the profile of bioactive compounds and AOX in an optimized ultrasound extract with a thermal extract. The optimized parameters for UAE included exposure to light, 1 s ultrasound pulse, 8 min extraction, 40 % amplitude, 60 °C extraction temperature, 20 % (v/v) ethanol, 35:1 (v/w) liquid-to-solid, and 850 µm particle size and showed gallic acid content of 1.97 mg/g MS. The thermal extract had a higher total soluble phenol content, mainly composed of gallates and gallotannins. Nevertheless, specific compounds, such as maclurin galloyl glucoside and quercetin xyloside, were uniquely identified in the UAE-optimized extract. DPPH and ABTS values were higher in the thermal extract. The half-maximal inhibitory concentration for the thermal treatment was 15.93 mg, while for UAE, it was 19.77 mg GAE/mL. Both thermal and ultrasound mango seed extracts exhibit significant potential as functional ingredients due to their high content of polyphenols and AOX.